<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <input type="range" min="2">
    <input type="color" >
    <script>
var temp;
var apple1 = '青苹果';
var apple2 = '红苹果';
temp = apple1;
apple1 = apple2;
apple2 = temp;
console.log(apple1); // 输出结果：红苹果
console.log(apple2); // 输出结果：青苹果
var str1 = 'I\'m a programmer';
console.log(str1.length);
var age = prompt('请输入您的年龄'); // 弹出一个输入框，让用户输入年龄
var msg = '您今年' + age + '岁了';    // 将年龄与输出的字符串拼接
alert(msg); 
console.log(typeof 12);	            // 输出结果：number
console.log(typeof null);	            // 输出结果：object
var a = '12';
console.log(typeof a == 'string');  // 输出结果：true 
console.log(typeof NaN); //输出为number
console.log(typeof NaN); //输出为number
alert('凯哥'); 
</script>
</body>
</html>